1. Field of the Invention
The invention relates to audio processing systems and particularly customized audio adjustment systems.
2. Description of the Related Technology
Active noise reduction; active noise cancellation and active noise control are known in the prior art Elliot, S. J. et al., “Active Noise Control,” IEEE Signal Processing Magazine, October 1993 (pages 12-35), the disclosure of which is expressly incorporated by reference herein, describes the history and background of active noise control systems and describes the use of adaptive filters.
Kuo, Sen M. et al., “Active Noise Control: A Tutorial Review,” Proceeding of the IEEE, Vol. 87, No. 6, June 1999 (pages 943-973), the disclosure of which is expressly incorporated by reference herein, describes principles and systems for active noise control.
Kuo, Sen M. et al., “Design of Active Noise Control Systems with the TMS320 Family,” Application Report, Texas Instruments Digital Signal Processing Solutions, Digital Signal Processing Products-Semiconductor Group, SPRA042, June 1996, the disclosure of which is expressly incorporated by reference herein, describes specialized digital signal processors designed for real-time processing of digitized signals and details the design of an Active Noise Control (“ANC”) system using a TMS320 DSP.
United States Published Patent Application US 2014-0044275, the disclosure of which is expressly incorporated by reference herein, describes an active noise control system with compensation for error sensing at the ear drum including a subjective tuning module and user control.
Active noise control systems utilize various active filtration techniques and rely on algorithms to process source audio in order to reduce the influence of noise on the listener. This may be accompanied by modification of the source audio by combination with an “anti-noise” signal derived from comparing ambient sound to source audio at the ear of a listener.
Active noise control devices in the prior art suffer from being incapable of addressing the wide variation of ambient sound, dominant noise, acoustic sensors, specific characteristics of headphones or earphones or other listening devices, the type nature and characteristics of source audio (such as sound from a digital electronic device), and individual audio perceptions as each of these and other elements of sound interact to comprise a listening experience.
Adaptive noise cancellation is described in Singh, Arti. “Adaptive Noise Cancellation,” Dept. of Electronics & Communications, Netaji Subhas Institute of Technology, (2001). http://www.cs.cmu.edu/naarti/pubs/ANC.pdf#. Accessed Nov. 21, 2014, the disclosure of which is incorporated herein. The customization according to the invention may be performed in accordance with the principles described therein.
Advancements in hearing aid technology have resulted in numerous developments which have served to improve the listening experience for people with hearing impairments, but these developments have been fundamentally limited by an overriding need to minimize size and maximize invisibility of the device. Resulting limitations from miniaturized form factors include limits on battery size and life, power consumption and, thus, processing power, typically two or fewer microphones per side (left and right) and a singular focus on speech recognition and speech enhancement.
Hearing aid technology may use “beamforming” and other methods to allow for directional sound targeting to isolate and amplify just speech, wherever that speech might be located.
Hearing aid technology includes methods and apparatus to isolate and amplify speech and only speech, in a wide variety of environments, focusing on the challenge of “speech in noise” or the “cocktail party” effect (the use of directional sound targeting in combination with noise cancellation has been the primary approach to this problem).
Hearing aid applications typically ignore or minimize any sound in the ambient environment other than speech. Hearing devices may also feature artificial creation of sounds as masking to compensate for tinnitus or other unpleasant remnants of the assistive listening experience for those suffering from hearing loss.
Due to miniature form factors, hearing aids are constrained by a severe restriction on available power to preserve battery life which results in limitations in signal processing power. Applications and devices not constrained by such limitations but rather focused on providing the highest quality listening experience are able to utilize the highest quality of signal processing, which among other things, will maintain a high sampling rate, typically at least twice that of the highest frequency that can be perceived. Music CDs have a 44.1 kHz sampling rate to preserve the ability to process sound with frequencies up to about 20 kHz. Most hearing devices sample at rates significantly below 44.1 kHz, resulting in a much lower range of frequencies that can be analyzed for speech patterns and then amplified, further necessitating the use of compression and other compensating methodologies in an effort to preserve the critical elements of speech recognition and speech triggers that reside in higher frequencies.
Hearing aids have almost always required the need to compensate for loss of hearing at very high frequencies, and given equivalent volume is much higher for very high and very low frequencies (i.e., more amplification is required to achieve a similar volume in higher and lower frequencies as midrange frequencies), one strategy has been compression (wide dynamic range compression or WDRC) whereby either the higher frequency ranges are compressed to fit within a lower frequency band, or less beneficially, higher frequency ranges are literally cut and pasted into a lower band, which requires a learning curve for the user.
For these reasons hearing aid technologies do not adequately function within the higher frequency bands where a great deal of desired ambient sound exists for listeners, and hearing aids and their associated technologies have neither been developed to, nor are capable as developed, to enhance the listening experience for listeners who do not suffer from hearing loss but rather want an optimized listening experience.
Noise reduction systems have been implemented in such a way that their use and processing is fixed across listening environments in either an On/Off paradigm or a degree of noise reduction setting, or on a frequency-specific basis utilizing multi-channel processors to apply noise reduction within specific frequency bands, however, in each of these systems, other than identifying speech within a hearing aid application, these noise reduction systems have treated all ambient noise as a single class of disturbance.
Typical hearing devices utilize either a system of a) isolating steady-state sound or other ambient sounds that do not correspond to predetermined modulation rates and peak to trough characteristics or b) measure signal to noise ratios in an ambient environment which all assume the desired “signal” is speech, or within frequency bands in a multi-channel system to similarly isolate environments in which signal to noise ratios are high (all ambient sound is not too loud and thus lower or no noise suppression across frequencies or within frequency bands is applied) or in which signal to noise ratios are low (all ambient sound is deemed to be too loud/undesirable and thus more noise suppression is applied), but the invention will allow similar systems to be employed with the fundamental and unique attribute that they will allow the listener to determine which sounds or signals in the ambient environment are desirable and to similarly determine which signals or sound profiles constitute undesired noise, thus enabling the established methodologies of utilizing modulation and other sound pattern or signal to noise methodologies to be employed in the current invention. These methodologies may incorporate the inclusion of speech, in general, as the relevant signal, or may further refine the characteristics of that speech to associate the signal with the speech of a child or of children, or certain specific individuals or sounds which incorporate speech as part of their acoustic signal, but will also focus on the limitless combination of ambient sound which are, in fact, desirable and not group all such sounds into a single group as has been done in the prior art. Headphone, earphone and other listening devices have focused on the reproduction of source audio signals at the ears of listeners and have all been developed with the assumption or belief that such source audio signal is the only source of desired sound. These listening devices later incorporated one or more microphones either for use in noise cancellation or to enable the listening devices to function as the speaking and hearing components of wireless communication devices, recognizing the benefit to users of not having to remove such listening device when using such wireless communication system. In each of these incarnations and scenarios where users may wish to communicate with others in their presence, these listening devices have muted the source sound while activating the microphone.